The overall objective of this project is to study the binding of DNA to cationic bicelles (bilayer micelles) with the intention of using the bicelle as a model for charged phospholipid membranes that are important in DNA transfection experiments. Because gene therapy relies on having efficient ways of transferring appropriate DNA into the cell, it is important to have information on the formation and stability of cationic lipid-DNA complexes that can be used in transfection. The proposed work is divided into two segments, involving first the characterization by light scattering and differential scanning calorimetry of the cationic bicelles prepared from available cationic phospholipids mixed with micelle-forming phospholipids or neutral bile salt derivatives. Secondly, the binding of DNA to appropriate bicelles will be studied by isothermal titration calorimetry in order to evaluate binding constants and the energetics of interactions of the bicelle lipid with phosphates of the DNA. Additional work will focus on the thermal melting behavior of the complexes formed between DNA and cationic lipid. Binding energetics will be determined for bicelles with differing charge density in the bilayer and under a variety of solution conditions. In the end a profile of the energetics of formation of the complexes can provide vital information on the best conditions for the formation of transfection systems for gene therapy.